1. Field of the Invention
The present invention relates to a closed crankcase ventilation system and, more particularly, to a closed crankcase ventilation system in which blow-by gas is introduced into an oil separator through a blow-by gas blowout opening.
2. Description of Related Art
In general, the blow-by gas is composed of partially-oxidized mixed gas, combustion gas and incompletely-combusted mixed gas. About a quarter of hydrocarbons exhausted from a vehicle is included in the blow-by gas. Since the blow-by gas is strongly acid, it causes corrosion in the engine and deterioration of oil.
Accordingly, the blow-by gas is forwarded from a combustion chamber into the crankcase of the engine and discharged from the crankcase to a head cover. Because of this account the oil becomes thin or deteriorated under the influence of heat or moisture of the combustion gas, gasoline, etc., thus generating sludge. To this end, an oil separator is typically provided to receive the blow-by gas generated in the process of the combustion in the engine and filter oil included in the blow-by gas to recycle the blow-by gas to an intake and drain the oil and impurities into an oil pan.
In a conventional oil separator, to oil separation portion typically separates oil included in the gas by rotating the introduced gas in an internal space thereof to reduce the flow rate and make the oil in the gas to adhere to the wall surface thereof using the centrifugal force. However, since the passenger and commercial diesel engines have a structure in which the blow-by gas is blown out from a rocker cover to be recycled, especially, overhead camshaft (OHC) engines have a relatively larger amount of oil and impurities due to the lubrication of cams, rocker shaft, etc.
Accordingly, at an early stage of designing the passenger and commercial diesel engines in which the oil consumption amount and the blow-by gas amount are relatively large, it is necessary to improve the durability of the turbo and intercooler system and to prevent the piston rings from being worn away due to carbons generated in the combustion chamber. Moreover, it is necessary to design the oil drain portion to be submerged in the oil at all times to prevent oil from flowing backward.